Pulse reception system



Dec. 5, 1950 D. HINGS 2,532,450

PULSE RECEPTION SYSTEM Filed Aug. 6, 1945 s Sheets-Sheet 2 INVENTOR :W I1 BY M ATTORNEY? Dec. 5, 1950 D. L. HINGS 2,532,450

EULSE RECEPTION SYSTEM Filed Aug. 6, 1945 3-Sheets$heet 3 llll"milmulill I W;WHIHHHHIMII' A FMVTWNWVWWWPWWMWW INVENTOR Dwwi a. #14 0 BYWM ATTORNEYS.

Patented Dec. 5, 1950 UNITED STATES PATENT QFFICE 2532350 PULSEREoEPTIofi s'iisriiwi Donald L. Ilings Ottawa, fintariii; estate; as-

signor, by mesiie assignments, to 'Go'i'iiell Dubilier ElectricCorporation; South Plainfleld, N. J., a. corporation of DelawareApplication Auguste, 1945, twat In Canada July 20, 1945 (or 250 20) 8Claims; I

My invention relates to a pulse reception sy's-"- tem and moreparticularly to a pulse reception system having both pulsed continuouswaves and interference waves between which discrimination is made forthe purpose of establishing a control circuit to govern a currentresponsive device.

An object of my invention is the provision of a reception system havingboth pulsed continuous waves and interference waves, together with meansduring the spacer intervals for utilizing the energy from theinterference waves and for neutralizing both the pulsed continuous wavesand the interference waves during the marker intervals.

Another object of my invention is the provision in a pulse receptionsystem (if injecting generated interference waves over and above theinherent spurious interference waves, whereby' an increased amount ofenergy is available M during the spacer intervals for utilization as ameans of control to govern a current responsive device which generates asecondary pulsed continuous wave which has substantially the same timeconstants as the primary pulsed continuous waves;

Another object of my invention is the provision, in a pulse receptionsystem, of means for injecting energy into the system which is availablefor control purposes during the spacer intervals of the pulsedcontinuous wave.

Another object of my invention is the provision, in a pulse receptionsystem, which neutralizes the pulsed continuous waves during the markerintervals and which provides a source of control energy during thespacer intervals;

Another object of my invention is the provision, in a pulse receptionsystem, of providing full-wave rectification of the interference wavesand thereafter peak limiting the rectified energy to give a controlcurrent of relatively constant amplitude throughout the period of thespacer intervals.

Another object of my invention is to inject, into a pulse receptionsystem, interference energies having a larger magnitude than that of thespurious interference energies.

Another object of my invention is to provide for injecting modulatedinterference waves in a pulse reception system to make the systemreceptive to modulated pulsed carrier waves.

Another object of my invention is the provision, in a pulse receptionsystem, of discriminating between modulated pulsed carrier waves andmodulated interference Waves.

Other objects and a fuller understanding of my invention may be had fromthe following description and claims, taken in conjunction with theaccompanying drawings; in which:

Figure 1 represents a diagrammatic view of a 2 pulse retention systemembodying the features of my invention;

Figure 2 is a view of a pulsed continuous wave which is shown as beingfree of all interference waves and is shown as having a fading amplitudecomponent.

Figure 3 is a view of a spurious interference wave which is present innormal atmospheric reception.

Figure 4 shows a view of a discharge inter rerenee wave; having a randompeaked envelope; which may be injected into my pulse reception system.

Figure 5 shows a view of the combination energy waves comprising boththe spurious intrferen'ee energies andthe injected interfereiice'energies, with the amplitude of the energies limited;

Figure 6 is a view of a radio frequency wave produced by detecting theenergy wave of Fig" ure 5;

Figure 7 is a view of the amplitude Wave in Figure 6, after thefrequency or the wave in Figure 6' has been doubled, the energyrectified and the amplitude (if the energies limited to a predeterminedlevel.

Figure 8 is' a view representing an energy wave produced by filteringthe wave of Figure '7;

Figure 9 is a pulsed continuous wave generated by a secondary source ahagoverned. in response to the energies obtained during the spacerinterval's from the interference waves.

Figure rc shows a modified pulsed continuous wave, generated from thesecondary source and having aninverse time constant with respect toFigure 9'. but of the same time constant as of Fig ure 2 which shows theprimary pulsed continuous wave;

Figure I1 is a view of a modulated pulsed carrier wave.

Figure 12 is a" view similar to Figure 3.-

Figure 1-3 is a view similar to Figure 4 with modulation on theinterference waves.

Figure 14 is a view similar to Figure 5'; but pro: duced" from themodulated discharge wave en: velope shown in Figure 13 controlled by"the wave of Figure 11.

Figure I5 is' a view similar to Figure fiybut produced from the energywave shown in Figure 14;

Figure 16 is a view similar to Figure '7, but pro duced from the waveshown in Figure 15.

Figure 17 is a view similar to Figure 8, but produced from-the waveshown in Figure 16.

Figure" '18 is a view similar to Figure 9;

Figure 19 is a view similar to Figure 10'.

With reference to Figure 1- oftlie' drawing, the reference character f0represents a transformer having a primary winding H adapted to receivepulsed continuous waves having on and on periods to produce alternatespacer and marker intervals which may come from pulsed transmissions ofintelligence such, for example, as a pulsed continuous wave employed inthe operation of a teleprinter or other device. A condenser I2 isconnected across the primary winding l l and the two constitute a tunedcircuit which may be tuned substantially to resonance at a frequencyequal to the frequency of the incoming carrier waves.

My invention preferably provides for injecting interference waves intothe transformercircuit, whereby the transformer delivers both pulsedcontinuous waves and injected interference waves. The injection of theinterference waves into the pulsed continuous waves may be done byemploying an interference wave generator l3, which may be connected tothe transformer circuit by a switch 33. For certain conditions, theinterference waves may be modulated by waves from a selective or lowfrequency generator l4. A switch If: connects the selective frequencygenerator M to the interference wave generator l3. When the switch I isclosed, the interference waves injected into the pulsed reception systemare modulated as shown in Figure 11. When the switch 15 is open, theinterference waves injected into the pulsed continuous wave system havea random discharge wave envelope, as shown in Figure 4. The constructionand arrangement of the interference wave generator l3 and thelow-frequency generator I may be substantially the same as those shownin my pending application, executed concurrently herewith, entitledDischarge Wave Generator, Serial Number 609,259, filed August 6, 1945,now Patent No. 2,468,754 granted May 3, 1949.

Figure 2 may represent a pure pulsed continuous wave which is excited inthe transformer Ni, without the presence of the spurious interferencewaves which exist in reception under normal atmospheric conditions.Figure 3 shows a representation of a spurious interference wave as maybe found in reception. In actual operation, the incoming energy receivedfrom the pulsed continuous wave transmitter would be a combination ofFigures 2 and 3. Figure 4 shows a representation of an interference waveas delivered by the interference wave generator 13 without thelow-frequency wave generator M being connected into the circuit.

In actual operation, the wave energies excited in the secondary windingN5 of the transformer would be a combination of the waves shown inFigures 2, 3 and 4. In my invention, the injected interference energiespreferably have a larger magnitude than that of the spuriousinterference energies. A condenser I1 is connected across the secondarywinding i6 and provides in combination therewith a tuned circuit whichmay be tuned substantially to resonance at a frequency substantiallyequal to the frequency of the incoming pulsed continuous waves. Theenergy delivered by the secondary winding l6 and the condenser H isdetected and limited by a duodiode rectifier l8 comprising two plates I9and 2E! and two cathodes 2i and 22. The plate l9 and the cathode 22 areconnected to the upper terminal 23 of the secondary winding l6. Thecathode 2| is connected to ground and to the lower terminal 2 3 of thesecondary winding l6 through a high-frequency by-pass condenser 25.

A .battery 26 is connected between the plate 26 and the cathode 2!. Theplate l9 and the cathode 2i constitute a part of the detector circuitwhich comprises the resonant circuit l6 and if and the fixed resistor 21and the adjustable resistor 28. The fixed resistor 21 in combinationwith condensers 25 and 29 constitutes a highfrequency filter and theadjustable resistor 28 constitutes a detector load resistance.

In actual operation, the piate i9 and the cathode 2! pass current fromthe secondary winding 16 until the voltage of the detector circuitreaches a value equal to the voltage of the battery 26, at which pointthe energy from the secondary winding [6 is conducted to ground througha circuit including the cathode 22, the plate 25 and the battery 26. Inmy invention, the potential of the battery Zfi and the design of thedetector circuit is such that the voltage generated in the detectorcircuit resulting from a detection of the pulsed continuous wave isalways greater than the voltage of the battery 26, whereby during themarker intervals the energy of the secondary winding [6 of thetransformer below the effective battery bias is conducted to the loadresistor 23 and the energy which is above the effective battery bias isneutralized. Thus, under the above condition, the pulsed continuouswaves during the marker intervals, as well as the spurious interferencewaves and the injected interference waves, are suppressed and preventedfrom flowing in the detector circuit. This condition is shown enlargedin Figure 6. However, the design of the detector circuit and the voltageof the battery 26 is such that a major portion of the energies from thespurious interference waves and the injected interference waves ispermitted to flow in the detector circuit, such as shown in Figure 6,the high peaked random amplitudes being cut off. In other words, thedetector circuit is such as to limit the amplitude of the detection ofthe spurious interference waves and the injected interference waves. Therandom peaked amplitudes of the spurious peaks in my invention may bemany times greater than the amplitude of the pulsed continuous waves,but they are limited by the action of the duo-diode rectifier [8. Thesame is true with respect to the amplitudes of the injected interferencewaves. This limiting action is shown in Figure 5, which shows thevoltage across the tuned circuit Iii-ll with no signal applied. Eventhough the amplitudes of the spurious interference waves and theinjected interference waves are limited to a predetermined value, yetthere are a multitude of tiny spaces there between, which envelope maybe detected below the level of the pre-determined value to which theyare limited. To further explain the operation of this part of mycircuit, I offer the following theory, but do not intend to be bound bythe consequences of any theory: During the spacer intervals, since theenvelope of the interference wave will periodically, at an audiofrequency rate, drop to zero or to a magnitude less than that of thepredetermined level of the battery bias, neutralization will not occurat these periods, and therefore an audio frequency voltage will appearacross the load resistor 28, to be passed to the next stage. Now duringthe marker intervals, the voltage of the incoming signal, that is, thepulsed continuous wave, being a continuous wave that has an envelopealways greater in magnitude than the effective battery bias, dominatesthe tuned circuit lfi-i'i to cause the positive half cycles passed bythe diode elements it and 2| to fully occupy the diode rectifying cycle.Therefore, the filtering action of the high frequency filter 25, 29 and2'! smooths out the high frequency half cycles to effectively produce adirect current component across the load resistor 28. as governed by theeffective battery bias. The rectification of the negative half cycles inexcess of the battery bias neutralizes that portion of the positive halfcycles in excess of the battery potential in the filter --2'l--29,thereby leaving only the direct current voltage from the diode |9--2l ata potential substantially proportional to the effective battery biasacross the load resistor 28. This neutralization of the high frequencycycles means that all alternating potentials are neutralized andtherefore no envelope exists. Thus the neutralization of the highfrequency cycles may also be considered as neutralization of theenvelope, which means that no signal is passed to the next stage duringthe marker interval.

The next process in my pulse reception system is to amplify the detectedenergy waves, and, as illustrated, I provide an amplifier 31 for thispurpose. The amplifier 3'! may comprise a plate 38, a cathode 35 and agrid 45. With the switch l5 open, which is the condition when nomodulation is applied to the injected interference waves, the detectedenergy from the resistor 28 of the detector circuit is coupled directlyto the grid to of the amplifier tube 37 by a condenser 36 through aswitch 3|. In other words, when the switch i5 is open, the switch 3 i,which is connected across the low-frequency pass filter, is closed. Theresistor 32 is the grid resistor for the grid 40 and the resistor 4! isthe cathode biasing resistor for the cathode 39. The condenser E2 is aby-pass for the cathode 39 to ground. The wave which appears in thecathode plate circuit of the amplifier tl'may be represented as similarto Figure 6, which is a high audio frequency wave, although in actualpractice the amplitude may be relatively greater than that shown inFigure 6, and it Will be symmetrical on both sides of the base line A.The plate-tocathode circuit of the amplifier 31 includes a primarywinding M of a coupling transformer 43 having a secondary winding 48.The plate 38 of the amplifier tube 35 is connected to a high voltagesource 55 through the primary winding i l. The condenser 45 is theby-pass for the waves fiowing through the primary winding 44.

The next operation in my invention is to full- Wave rectify theenergyreceived from the secondary winding 45 of the coupling transformer 53and thereafter limit the amplitude of the full-wave rectificationenergy. The full-wave rectification may be done by a duo-diode rectifier53 and the limiting may be done by a duo-diode rectifier 58. Therectifier 53 comprises two plates 54 and 55 and two cathodes 56 and 51.The rectifier 53 comprises two plates 59 and 60 and two cathodes 5| and62. The cathode 56 of the rectifier 55 and the plate 59 of the rectifier58 are connected to the upper terminal 4'! of the secondary winding 4'5.The cathode 5? of the rectifier 53 and the plate 55 of the rectifier 55are connected to the lower terminal 58 of the secondary winding 45. Theplates 5t and 55 of the rectifier 53 are connected to the negativeterminal of a battery 63 and the cathodes 5i and 82 of the rectifier 58are connected to the positive terminal of the battery 63. The outputvoltage representing the full-wave rectified and limited energy from thetubes 53 and 58 appears across the conductors 54 and 65, the conductor54 being connected to the plates 54 and 55 and the conductor 55 to thecenter tap 69 on the secondary 46. The rectifier 53 provides for givingfull-wave rectification to the wave energy supplied thereto until thevoltage appearing between the conductors 64 and 65 equals the voltage ofthe bat tery 63. The full-wave rectified and limited energy as appearingin the conductors 64 and 65 is represented by the waves in Figure '7.One object in providing full-wave rectification is that I am able toreduce the gap between the amp1itude of the waves and therebysubstantially double the frequency. The double frequency makes for asteady wave which may be more easily filtered than what it would be ifthe frequency were not doubled by the full-wave rectifier action.

The next operation in my invention is to utilize the interference waveenergies which appear in the conductors t4 and 55 as a means forproducing pulsed continuous waves from a secondary source, having spacerand marker intervals which have a time constant which may be either inopposite or in phase relation with the primary pulsed continuous wavesappearing in the transformer i 5. As illustrated in Figure 1, thevoltage across the conductors 64 and 55 controls a current responsivedevice which provides for giving a pulsed continuous wave such as thatshown in either Figure 9 or in Figure 10, depending upon the conditionsof the current responsive device. lhe current responsive device maycomprise a twin-triode amplifier 68, an audio oscillator $5, an audioamplifier 8i and a grid balancing circuit 85. The twin-triode amplifiercomprises two plates 59 and it, two grids ii and 2'2 and a centrallydisposed cathode T3. The two plates 59 and iii are connectedrespectively to the ends Ti and IS of the primary winding '55 of anoutput transformer Hi having a secondary winding it which suppliespulsed continuous waves. The cathode '53 is connected to ground througha cathode biasing resistor iii. A condenser 52 is connected across theresistor SI for lay-passing the cathode 1'3 to ground. The primarywinding '55 is provided with a center tap '38 which is connected to ahigh-voltage source 5%. The two grids ll and '52 are connected incircuit relation with the grid balancing circuit 533, which circuit inturn is coupled to the audio amplifier 8? through an adjustable couplingresistor t8. A condenser 59 couples the grid H to the coupling resistor88 and a condenser 96 couples the grid i2 to the coupling resistor 85.The conductors E i and 65 are respectivel connected to the ends of abalancing resistor 92 having an adjustable pointer which is connected toa biasing battery 9!. The resistors 53 and 94 are grid resistorsrespectively for the grids H and T2. The resistors 55 and 95 areconnected across the balancing resistor 52 and have their intermediatepoint connected to ground. The condenser 91 is a filter condenser andconnects the conductor 65 to ground. Similarly, the condenser 55 is afilter condenser and connects the conductor 64 to ground. The condensers9! and 93, in combination with the resistors 95 and 95 and 92, providefor filtering the voltage across the conductors 5:3 and @5, such asshown in Figure 8 of the drawmg.

For teleprinter use, when no voltage appears across the conductors itand 55, such as would be the case when the pulsed continuous Wave is atthe marker interval, then the two grids ii and 12 have the same biasthereon, which renders the twin-triode amplifier 58 inoperative. Thus,the output from the secondary winding 15 of the transformer is zeroduring the marker intervals of the incomin pulsed continuous waves tothe transformer iii. This condition is shown in Figure 9. During thespacer intervals, voltage appears across the conductors 6 3 and t5, andthus current flows through the balancing resistor 92 to offset the biasbetween the grids it and 12, so that the twin-triode amplifier 68becomes operative to produce an output during the spacer intervals, suchas shown in Figure 9, for teleprinter work. The alternating currentdelivered by the secondary winding l8 may be rectified for producingdirect current for direct operation of the teleprinter. The wave inFigure 10 is the inverse of the wave in Figure 9, and this inverse wavemay be obtained by ire-balancing the balancing resistor 82 such that nocurrent flows during the spacer intervals and such that current flowsduring the marker intervals, producing waves for oral or automaticreception of the primar pulses directly in proportion to theirintelligence of transmission.

Figures 11 to 19 correspond respectively to Figures 2 to 10, but withthe switch it closed, whereby the interference waves are modulated. Inother words, with the switch closed, the interference waves which areinjected into the transformer circuit it may be characterized as havinga modulated discharge wave envelope, such as shown in Figure 13. Wherethere is pure pulsed continuous wave reception, there is no need formodulating the interference waves. But, where the pulsed carrier wave ismodulated, as shown in Figure 11, I preferabl modulate the injectedinterference waves. Modulation of the interference waves is desirable,because the modulation occurring on the continuous wave signal causesthe voltage thereof to periodically become less than the voltage-of thebattery 25. This permits interference wave energy to appear in the loadresistor 28 during the marker intervals. It isthen necessary todiscriminate against the audio component of tone by passing the tonethrough a filter 3%, the filter 33 being selective to pass the frequencyof the selective frequency generator and not the frequency of themodulation of the carrier. ihe filtering, therefore, eliminates thepulses of interference wave energy during the marker intervals, as shownin the transition from Fig. 15 to Fig. 16. To facilitate discriminationbetween the modulation frequency of the carrier modulation frequency ofthe selective frequency generator it, the modulation of the generator itis purposely made of different frequency. Thus, I provide for closingthe switch l5 under this condition. When the switch 55 is closed, theswitch at is open for passing the detected energy through the selectivefrequency pass filter 38. In this event, the wave which is amplified bythe amplifier 3"? may be represented by the wave shown in Figure 15. Thewaves shown in Figures l5, 16, 1'7, 18 and 19 may be produced by thecircuit of Figure l in the same manner as the waves in Figures 6, 7, 8,9 and 16 were produced, except that the condensers St and B5 areconnected respectively in parallel with the condensers t? and 58 byclosing the switches 3t and 35. The condensers and are added to increasethe filtering capacities for the lower frequencies of the modulatedinjected interference waves. When using the selective frequencygenerator M for modulating the interference waves, I preferably fix thefrequency of the generator i l and the selective frequency pass filtertil at a frequency substantially different from the frequency of themodulation on the pulse carrier wave. In this manner, the low-frequencypass filter selects only the frequency produced by the generator M andit excludes the modulating frequency of the carrier wave. In myinvention, I preferably make the magnitude of the injected interferenceenergy greater than the magnitude of the spurious interference energy,so that the interference energy is maintained substantially at aconstant value, even though the energy of the spurious waves mayfluctuate.

In those conditions where the intelligence signal is Weak and thereceiver is adjusted to give maximum sensitivity, the spurious waves,even though originally small, become relatively large by the time theyreach the detector. Thus, the ratio between the signal energy and thespurious energy is small. Under this condition, the switch 33 may beopened and the circuit operated without the injection of separateinterference energy. Should the signal suddenly become strong, mycircuit still is operative, because the alternating current component ofthe signal is neutralized during the marker interval. Signalintelligence is conveyed by the periodicity of the marker intervals, andalso by the ratio of the duration of the marker intervals to the spacerintervals.

Although I have shown and described my invention with a certain degreeof particularity, it is understood that changes may be made thereinwithout departing from the spirit of the invention which are includedwithin the scope of the claims hereinafter set forth.

I claim as my invention:

1. A radio reception system for obtaining signal intelligence from anelectromagnetic carrier wave having recurring first periods with apotential less than a determinable voltage and having recurring secondperiods with a potential greater than said determinable voltage, saidcarrier wave having present therein an interference wave having anenvelope of a frequency lower than said carrier wave and with saidenvelope having at least periodically a magnitude less than saiddeterminable voltage, said system comprising circuit means, means forapplying said carrier Wave to said circuit means, a single stagedetector connected to said circuit means and including first and secondrectifiers connected in opposition, differential means for establishingan influencing voltage at substantially the magnitude of saiddeterminable voltage for influencing said second rectifier to reduce thevoltage output of said second rectifier, said rectifiers producing adifferential output alternating voltage during said first period fromenergy from said interference Wave and producing a differential outputvoltage during said second period from energy from said carrier andinterference waves with said output voltage having a characteristicpatterned in accordance with said influencing voltage.

2. The method of obtaining signal intelligence from an electromagneticcarrier wave having recurring first and second periods of lesser andgreater magnitudes, respectively, than a determinable voltage, saidcarrier wave having present therein an interference wave having anenvelope of a frequency lower than said carrier wave and with saidenvelope having at least periodically a magnitude less than saiddeterminable voltage, said method comprising, establishing aninfluencing voltage at the magnitude of said determinable voltage,detecting the first half wave pulses of said carrier wave, detecting theopposite half Wave pulses of said carrier wave above said determinablevoltage, and combining said detected energies in a common load toproduce thereacross an alternating voltage from said interference waveduring said first period with said alternating voltage having acharacteristic patterned in accordance with the envelope of saidinterference wave which is periodically below said determinable voltage,and to substantially eliminate across said load any said alternatingvoltage during said second period.

3. The method of obtaining signal intelligence from an electromagneticcarrier wave having recurring first and second periods with a potentialless than and greater than a determinable voltage, respectively, saidcarrier wave having present therein an interference wave having anenvelope of a frequency lower than said carrier wave with said envelopehaving at least periodically a magnitude less than said determinablevoltage, said method comprising, separately detecting the positive andnegative half wave pulses of said carrier wave, establishing aninfluencing voltage at the magnitude of said determinable voltage,influencing the threshold of detection of one of said half wave pulsesby said influencing voltage, and combining the detected.

energies to produce a differential output alternating voltage duringsaid first period from energy from those interference waves havingmagnitudes less than said determinable voltage.

4. A radio reception system for obtaining signal intelligence from anelectromagnetic carrier Wave having recurring first periods with apotential, of at least a given polarity, less than a determinablevoltage and having recurring second periods with a potential, of atleast said given polarity, greater than said determinable voltage, saidcarrier wave having present therein an interference wave and at leastthe combination of said waves having an envelope of a frequency lowerthan said carrier wave and with said envelope having at leastperiodically a magnitude less than said determinable voltage, saidsystem comprising circuit means, means for applying said carrier wave tosaid circuit means, a single stage detector connected to said circuitmeans and including first and second rectifiers connected in opposition,differential means for establishing an influencing voltage atsubstantially the magnitude of said determinable voltage for influencingsaid second rectifier to reduce the voltage output of said secondrectifier, said rectifiers producing a differential output alternatingvoltage during said first period from energy from said interference waveand producing a differential output voltage during said second periodfrom energy from said carrier and interference waves with said outputvoltage having a characteristic patterned in accordance with saidinfluencing voltage.

5. The method of obtaining signal intelligence froman electromagneticcarrier wave having recurring first and second periods, respectively, oflesser and greater magnitudes of at least a given polarity than adeterminable voltage, said carrier wave having present therein aninterference wave and at least the combination of said waves having anenvelope of a freqency lower than said carrier wave and with saidenvelope having at least periodically a magnitude less than saiddeterminable voltage, said method comprising, establishing aninfluencing voltage at the magnitude of said determinable voltage,detecting the first half wave pulses of said carrier wave, detecting theopposite half wave pulses of said carrier "iii wave above saiddeterminable voltage, and combining said detected energies in a commonload to produce thereacross an alternating voltage from saidinterference wave during said first period with said alternating voltagehaving a characteristic patterned in accordance with the envelope ofsaid interference Wave which periodically below said determinablevoltage, and to substantially eliminate across said load any saidalternating voltage during said second period.

6. The method of obtaining signal intelligence from an electromagneticcarrier Wave having recurring first and second periods with a potentialof at least a given polarity less than and greater than a determinablevoltage, respectively, said carrier Wave having present therein aninterferenee wave and at least the combination of said waves having anenvelope of a frequency lower than said carrier wave with said envelopehaving at least periodically a magnitude less than said determinablevoltage, said method comprising, separately detecting the positive andnegative half wave pulses of said carrier Wave, establishing aninfluencing voltage at the magnitude: of said determinable voltage,influencing the threshold of detection of one of said half Wave pulsesby said influencing voltage, and combining the detected energies toproduce a differential output alternating voltage bearing a relationshipwith said signal intelligence during said first period from energy fromthose interference waves having magnitudes less than said determinablevoltage.

7. A radio reception system for obtaining signal intelligence from anelectromagnetic carrier wave having recurring first and second periods,respectively, of lesser and greater magnitudes of at least a givenpolarity than a determinable voltage, said carrier wave having presenttherein an interference wave and at least the combination of said waveshaving an envelope of a frequency lower than said carrier wave and withsaid envelope having at least periodically a magnitude less than saiddeterminable voltage, said system comprising, means for establishing aninfluencing voltage at the magnitude of said determinable voltage, asingle stage detector operable from said combined Waves and having firstand second detector means, means for applying said influencing voltageto said single stage de tector, said first detector means detecting thefirst half wave pulses of said carrier wave, said second detector meansdetecting the opposite half wave pulses of said carrier wave above saiddeterminable voltage, and a common load for said detector means tproduce thereacross an alternating voltage from said interference Waveduring said first period with said alternating voltage having acharacteristic patterned in accordance with the envelope of saidinterference wave which is periodically below said determinable voltage,and to substantially eliminate across said load any said alternatingvoltage during said second period.

8. A radio reception system for obtaining signal intelligence from anelectromagnetic carrier wave having recurring first and second periods,respectively, with a potential of at least a given polarity less thanand greater than a determinable voltage, said carrier wave havingpresent therein an interference wave and at least the combination ofsaid waves having an envelope of a frequency lower than said carrierwave with said envelope having at least periodically a magnitude lessthan said determinable voltage, said system comprising, first and seconddetectors separately detecting the positive and negative half wavepulses of said carrier wave, means for establishing an influencingvoltage at the magnitude of said determinable voltage, means forinfluencing the threshold of detection of one of said detectors by saidinfluencing voltage, and means for combining the detected energies toproduce a differential output alternating voltage in accordance withsaid signal intelligence during said first period from energy from thoseinterference waves having magnitudes less than said determinablevoltage.

DONALD L. HINGS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,723,440 Ranger Aug. 6, 19292,087,063 McCutchen July 13, 1837 2,125,953 Prochnow Aug. 9, 19382,127,525 Marshall Aug. 23, 1938 2,193,825 Lowell Mar. 19, 19402,258,877 Barber Oct. 14, 1941 2,283,404 Wood May 19, 1942 2,243,115Noble Feb. 29, 1944 2,356,224 Crosby Aug. 22, 1944 2,361,437 Trevor Oct.31, 1944 2,383,126 Hollingsworth Aug. 21, 1945

